Liquid phase carbonylation processes such as the carbonylation of methanol and/or reactive derivatives thereof in the presence of homogeneous catalysts to produce acetic acid are operated commercially. Gas phase carbonylation processes employing methanol and dimethyl ether using heterogeneous catalysts are also known.
EP-A-0 596 632 describes a vapour phase process for the carbonylation of methanol to produce acetic acid at high temperatures and pressures in the presence of a mordenite catalyst which has been loaded with copper, nickel, iridium, rhodium or cobalt
WO 01/07393 describes a process for the catalytic conversion of a feedstock comprising carbon monoxide and hydrogen to produce at least one of an alcohol, ether and mixtures thereof and reacting carbon monoxide with the at least one of an alcohol, ether and mixtures thereof in the presence of a catalyst selected from solid super acids, heteropolyacids, clays, zeolites and molecular sieves, in the absence of a halide promoter, under conditions of temperature and pressure sufficient to produce at least one of an ester, acid, acid anhydride and mixtures thereof. However, the use of zeolites to catalyse the carbonylation reaction is not exemplified.
WO 2005/105720 describes a process for production of a carboxylic acid and/or an ester or anhydride thereof by carbonylating an aliphatic alcohol or reactive derivative thereof with carbon monoxide in the substantial absence of halogens at a temperature in the range 250-600° C. and a pressure in the range 10 to 200 bar in the presence of a mordenite catalyst which has been modified with copper, nickel, iridium, rhodium or cobalt and has as framework elements, silicon, aluminium, and at least one of gallium, boron and iron. The use of dimethyl ether as a feedstock is not exemplified.
WO 2006/121778 describes a process for the production of a lower alkyl ester of a lower aliphatic carboxylic acid by carbonylating under substantially anhydrous conditions a lower alkyl ether, such as dimethyl ether, with carbon monoxide in the presence of a mordenite or ferrierite catalyst. The use of a gallium framework modified mordenite as catalyst for the carbonylation of dimethyl ether is exemplified
In view of the above-mentioned prior art, there remains the need for an improved heterogeneous gas phase process for the production of methyl acetate from dimethyl ether under substantially anhydrous conditions using a zeolite catalyst.